Radiosignaling system



0. LE sl FORTESCUE. RADIOSIGNAUNG SYSTEM- API'LICATION FI LED DEC-2. 1916- RNEWED NOV. 8, I9".

Patented May 20, 1919.

INVENTOR Char/es L26. Fbrfestue WITNESSES:

AfroRNEY UNITED STATES PATENT OFFICE;

CHARLES LE G. FORTESCUE, OEPITTSBURGH, PENNSYLVANIA. ASSIGNOR TO WEST- INGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

namosronanme srsrnm.

. uterited May 20, 191%).

Application filed December 2, 1916, Serlal lo. 134.804. Renewed November 8, 1918. Serial No. 261.741.-

To all when) it may concern Be it known that I, Cuannns Li: G. Fon- 'rnscri-l, a subject of the King of England,

and a resident of Pittsburgh, in the county 'of .\lleghen v and State of Pennsylvania,

that are projected through space without the use of conducting wires.

More particularly, my invention relates to improvements in space-signaling or radiotelegraph systems that embody means for controlling the highfrequency oscillating circuits thereof which are supplied with energy from alternating-current sources.

It isrecognized that, to render the receiving apparatus of a radio system most effective, the impulses impressed upon the receiving circuit should occur at the rate of approximately 1000 impulses 'per second, which corresponds to the frequency or pitch of a tone of good audibility. To insure uniformity in the production of the tone in the receiving circuit and also the production of a note having a constant pitch, these impulses should be produced at regular, as

well as frequent, intervals." Moreover, the

' loudness of the tone produced in the receiving circuit depends upon the amplitudes of the impinging wave trains. This last propproduced at a high rate and uniform .frequency in order to insure the production of a lllllf( )l'll1l pitched and audible note in a distant receiving "station. these results without using a high-frequency alternator but by employing the usual Hertzian' oscillator.

For a better understanding of the nature and scope of my invention, reference may erty is secured over long distances by gen erating wave trains at the sending station that are only slightly damped or ossess a a low decrement. It is apparent, tierefore,

that the wave trains originating in the sending stationshould be produced at regular intervals andv with suitable frequency, as

.well as, with high initial amplitudes in order to radiate from the antenna a series of wave trains that may be projected over wide spaces and be instrumental in producing, in the geceiving apparatus, audible notes of constant pitch or'uniformity.

An object of my present invention, therefore, is to provide means for accomplishing the afolementioned results, whereby radiations that are only slightly damped may emanate from the antenna of ,awireless fiding station. At the sametime, the wave trains projected into space may be be had to'thefollowing description and the accompanying drawingin which Figure 1 is a diagrammatic view of a radio-telegraph system that embodies a form of my inven I accomplish,

tion. and Fig. 2 is asimilar view for illustrat-ing one arrangement I comprising the circuits of Fi". 1. In Fig. 1, a source 1 of alternating current is connected, by means of conductors 2 and 3, to a primary winding 4 of a transformer 5. One secondary winding 6 of the transformer is connected in closed circuit with an adjustable condensive reactance elefor the apparatus former. are closely'magnetically linked with each other. The capacity of the condensive 'inent 7 The windings; and 6 of the transreactance element 7 is so chosen that-- its effect in the circuit comprising the primary winding 4 will, under certain circumstances, completely compensate for the inductive reactive drop'in said circuit when subjected to the flow of alternating currents having the frequency of those generated" by the source 1. In other words, the circuit comprising the primary winding 4 may operate, in certain instances, at unity powerfactor since the condenser 7 will completely compensate for the inductive reactance 0btaining therein.

A secondary wmding 8 of the trans former supplies power to a high-frequency oscillating circult 9. The circuit 9 coinprises w an oscillation producer 10, an adjustable condensive reactance element 11 and a primary winding 12 of an oscillation transformer 13,=-'which mat-1y commonly employe in connection with radio systems, A secondary'winding 1* of the osc-illation transformer'has one of its terminals grounded at 1? and thepther con-.v nected, through an ad ustable inductance device 15, teen antenna or electrical wave.

radiator 16.

The windings 8 and 4 of the transfor er be of any usual form- 5 are loosely magnetically linked with each other and, therefore, a leakage flux will obtain between the primary or inducing winding 4 and the said secondary winding, under certain'operating conditions.

The windings 12 and 14 of the transformer13 may be loosely or closely coupled. The coupling action 'is augmented when the primary and secondary circuits of the transformer 13 are in resonance. groper quenching of the sparks generated y the oscillation producer 10 is effected, the oscillations in the circuit comprising the primar winding 12 will discontinue after a very -s ort time-interval. The secondary circuit, therefore, will continue to oscillate at its natural frequency and with its natural damping just as if theprima'ry circuit did not exist. I

The oscillation producer 10,. in this instance, is shown as comprising a pair of' spaced electrodes 17 and 18 which are ad- 'ustable. The oscillation producer 10 may e any of the usual forms commonly emplolyed in connection with wireless systems. he capacity of the condensive element 11 is so chosen that the circuit comprising said element, the secondary winding 8 and the primary winding 12 of the oscillation transformer is in resonance with the circuit comprising the primary winding 4 of the trans; former 5, when the oscillation producer 10 is inactive. In other words, series resonance conditions are established between these'two circuitssince the condenser 11 inserts a condensive reactance that resonates with the inductive reactance inserted by reason of the leakage flux obtaining between the windings 4 and 8. Ofcourse, these series resonance conditions obtain for the normal frequency of the generator.

To produce high-frequency oscillations in the primary circuit of the oscillation transi former 13, the sparkgap between the elec- 10 is'disrupted by the voltages impressed I so.

trodes 17 and 18 of the oscillation producer thereupon by the secondary winding 8. The

initial breakdown being thus effected, high-- frequency oscillating currents will flow in the primary winding 12 by reason of the rapid charging and discharging of the condenser 11. The amplitudes of the high-frequency currents thus generated are constantly decreasing in value because of the damping action of the primary and secondary circuits. This is a usual way of generating electromagnetic oscillations which are to be radiated from the antenna of a radio system. It will be noted that, each time a discharge is efi'ected between the electrodes 17 and 18, a wave train will be ropagated into s ace from the antenna 16. ach wave train ti'lus emanated will produce a single impulse in the receiving apparatus of a distant receiving station.

Again, if

To produce audible notes of proper and unlform pitch, as well as loudness in the receiving apparatus, it is desirable to generate wave trains in the order of 1000 per second,

' with uniform regularity and frequency. To

between the exciting current traversing, and the resulting flux generated by, the inducing winding 4 and between said flux and the production of a sufiicient voltage in the secondary winding 8 to break down the sparkgap of the oscillator 10 should be substantially zero. k

The condenser 7, by reason of its association with the winding 6, compensates for the inductance obtaining in the circuit of the primary winding 4: only when the oscillation producer 10 is active. As a result, the maximum flux threading through the primary winding 4 is coincident in time with the mammum voltage or the peakofthe'alter na'tlng-current wave generated by the alternator 1, when the condenser 11 is rapidly charging and discharging through the oscillation' producer 10.

When the voltage obtaining in the secondary Winding 8 is sufficient to break down the spark-gap of the oscillation producer 10, the condenser 11 will discharge through the oscillation producer, thereby generating high-frequency oscillations in the oscillating circuit 9. Simultaneous therewith, the sec- 10 ondary winding 8 will be short circuited by reason of thespark discharge obtaining in the oscillation producer. At the same time, however, the circuit comprising the primary winding 4 will operate at unity power-factor 10 b reason of the action of the condenser 7. he value of the flux generated by the primary winding 4 is, therefore, independent of the conditions obtaining in the high-fiequency oscillating circuit 9. 4

When these conditions exist. the voltage induced in the secondary winding 8 is likewise coincident in time with the magnetic flux generated by the primary winding 4,

because the circuit comprising 'the short-cir- 11 cuited secondary winding 8 is in resonance with the circuit comprising the primary winding 4'. In other words, this combination of circuits isstuned to the frequency of the source ofdsgpplyx 1.

The highQfi e quency currents generated in the oscillating circuit 9 are substantially,

precluded from flowing through the secondary winding 8 because of the large reactance obtaining in said winding. By reason of the 15 large magnetic leakage between the. windings 4 and 8, the high-frequency currents are also substantially precluded from inducing any currents in the primary winding 4. The

energy of the high-frequency currents is, 1

therefore, confined to the high-frequency circuit 9 and the circuit comprising the antenna. 16.

From the foregoing description, it will be apparent that the wave trains are rapidly generated, since the conditions obtaining in the secondary winding 8 are in accurate timephase with the conditions obtaining in the primary windin 4. Again, the wave trains are rapidly pro need with high initial amplitudes' and, moreover, they possess a low the transformer 5 of Fig. 1. It will be noted that, the primary winding 4 is disposed on the same core leg as the secondary winding 6. The windings 4 and 6 are, therefore, closely magnetically linked with each other. The secondary winding 8 is disposed on a i second'core leg. Magnetic shunts and 21 provide means for increasing or varying the magnetic leakage between the primary winding 4 and the secondary windin 8. By

properly positioning the magnetics unts, 20

and 21, series resonance may be established between the winding 1 and the winding 8 in combination with the condensive reactance element 11. The primary winding 4 is impressed with alternating currents of the pro r frequency, in .this case, the frequency f t e currents generated by the alternator 1. While I have shown and described one embodiment of. my invention, I desire that only such limitations shall be imposed thereupon as are indicated in the appended c aims.

I claim as my invention:

1. In a system of radio-signaling, the combination with alternating-current source of supply and a high-fre uency oscillating circuit, of a transformer or interconnecting said circuit to said source, said transformer comprising a primary winding which is connected to said source, a secondary winding closely ,magneticall linked with the rimary winding, a secon secondary win ing a loosely magnetically linked with the rimary winding, a condensive reactance e ement connected in circuit with said first secondary winding, and means for connecting the high-frequency oscillating *circuit to said second secondary winding.

2. The combination with a source of alternating-current supply ands high-frequency that is connected to said source, one secondary-winding that is closely magnetically linked with the primary winding, a condensive rcactancc elcmentconnectcd to said secondary winding, and a second sccondar winding loosely magnetically linked with the primary winding, said second secondary winding bcing conn'ected in. shunt to'said oscillation producerand in series with said first condensive reactance clement.

3. The combination with a source of alternating-current supply and a high-frequency oscillating circuit comprising a condenser and an oscillation producer, of a transformer for interconnecting said source and said, oscillating circuit, said transformer comprising a primary winding, a secondary winding closcl magnetically linked therewith, a SQCOIK secondary winding loosely magnetically linked therewith and connected to the oscillating circuit, the capacity of said condenser ot' the oscillating circuit being of such value as to establish series-resonance conditions between said primary winding and the circuit comprising said second sccondary winding, under normal conditions, and a condenser connected in circuit with said first secondary winding to compensate for the inductive reactance of the circuit comprising said primary winding when the resonance conditions between the primary winding and said second secondary winding are disturbed.

. 4. The combinationwith a source of alternating-current supply and an energy-consuming circuit comprising a condensive .reactanceelement, of a transformer for interconnecting said source and said circuit with each other, said transformer comprising a primary winding, a secondary winding which is loosely magnetically coupled therewith and also connected in circuit with said condensive element whereby series resonance 3 conditions may obtain between the circuits comprising said transformer windings, a second secondary winding closely magnetically'linked with said primary winding, and a condensive reactance element connected in circuit with the second secondary winding for establishing resonance conditions in the circuit comprlsing the primary wlnding when theresonance conditions between the primary winding and the said first secondary winding are disturbed.

5. The combination with a supply circu t, a transformer comprising a primary w1nding, a secondary winding closely magnetically linked therewith, and a second secondary winding loosely magnetically linked therewith, of a condenser connected in c1rcnit with said second secondary winding to establish resonance conditions between the primary and saidsecondary windings, and another condenser connected in circuit wlth said first secondary winding to compensate for theinductive reactive drop in the circuit comprising the primary winding when reso- Ill nance conditions between the primary winding and said second secondary winding are d'estro ed.

6. he combination with a supply circuit, a transformer comprising a primary winding, a secondary winding closely magnetically linked therewith and a second secondary winding loosely magnetically linked therewith, of a condenser connected in circuit with said second secondary winding to establish series resonance conditions between the primary and second secondary windings, and a condenser connected in circuit with said first secondary winding to establish resonance conditions in the circuit comprising the primary winding when the series resonance conditions between the primary winding and said second secondary winding are dlsturbed.

7. The combination with a supply circuit,

a transformer comprising a primary winding, asecondary winding closely magnetically linked therewith and a second secondary winding loosely magnetically linked therewith, of a condensive react-ance element. connected in. circuit with the said second secondary winding to completel neutralize the effects of the leakage flux be primary winding and said second secondary winding, anda condensive reactance element connected in circuit with said first secondary winding for completely neutralizing the in ductive reactive drop in the circuit compris-' ing the primary winding when the condensive element connected 1n circu t with said second secondary winding falls tomamtam resonance conditions between the primary winding and said second secondary winding.

subscribed my name this 23rd day of Nov.

CHARLES LE G. FORTESCUE.

In testimony whereof, -I have hereunto tween the w 

